The PZT actuation on the laser frequency in MHz/V ( assuming the previous calibration here of the PZT count/V) is :
X- arm: 33.7 MHz/V
Y- arm: 14.59 MHz/V
This number seems to be wrong by a factor of 10.
So we[I and EricQ] decided to trace the cables that run into the ADC from the PZT Out. We found a black LEMO box in the path to ADC,which is an anti-aliasing filter for each input channel. However,in theory the response of this filter should be flat up until a few kHz i.e. for the DC gain it should be 1. But we will manually test it and look at the DC gain of the LEMO box.
I did the following with the PZT Driver Board:
With an expansion card attached to the driver board, I used an Agilent E3620A power supply to verify that the 15V and 24V supplies were reaching the intended ICs. It turns out that the +24 V supply was only meant to power some sort of on-board high voltage supply which provided the 100V bias for the PZTs and the MJE15030s. This device does not exist on the board I am using, jumper wires have been hooked up to an SMA connector on the front panel that directly provides 100V from the KEPCO high voltage supply to the appropriate points on the circuit.
All the AD797s as well as the LT1125CS ICs on the board were receiving the required +15V.
The next step was to check the board with the high-voltage power supply connected.
The output from the power supply is drawn from the rear output terminal strip of the power supply via pins TB1-2 (-OUT) and TB1-7 (+OUT). I used a length of RG58 coaxial cable from the lab and crimped a BNC connector on one end, and stripped the other to attach it to the above pins.
There are several options that can be configured for the power supply. I have left it at the factory default: Local sensing (i.e. operating the power supply using the keypad on the front of it as opposed to remotely), grounding network connected (the outputs of the power supply are floating), slow mode, output isolated from ground.
I then hooked up a function generator in order to simulate a control signal from the DAC. The signal was applied to pin 2 of the jumpers marked JP1 through JP4 on the schematic, one at a time. The signal applied was a 0.2 Vpp, 0.1 Hz sine wave.
Continued with tests on the PZT driver board. I made a few changes to replace defective components and also to modify the gain of the HV amplifier stage. I believe the board has been verified to be satisfactory, and is now ready for a piezo to be connected, tested and calibrated.
Revised Wiring Diagram:
DAC Max. Output Trace on Oscilloscope
I have updated the schematic of the D980323 PZT driver boards to reflect the changes made. The following changes were made (highlighted in red on the schematic):
I have also changed the routing of the 100V from the HV power supply onto the board, it is now done using an SMA T-connector and two short lengths of RG58 cable with SMA connectors crimped on.
The boards are functional (output swings between 0 and 100V as verified with a multimeter for input voltages in the range -10V to +10V applied using a function generator.
The four IOO PZTs have been turned on in order to confirm the alignment of the IFO.
Once they are turned on, the spots (ITMX/ITMY/PRM/SRM) on the REFL CCD have been easily found.
When the X-arm was aligned to the green beam, it is easily locked to TEM00. Also some LG modes were visible.
i.e. There is some room to improve the mode matching.
The transmitted green at the PSL table is a bit too high and clipped by the first mirror on the table.
No IR flashes were found in either arms.
The below are the range and the set values of the strain gauge readback for the PZTs.
When the closed loop buttons are activated the PZTs are fixed at those values, if no one touches the set point dials.
Min Max SetP | Display on the module
PZT1 Yaw 2.20 9.95 6.08 | Broken
PZT1 Pitch -0.011 8.89 4.40 | 1.58
PZT2 Yaw 0.737 9.94 5.37 | 2.17
PZT2 Pitch 0.010 9.42 4.71 | 1.89
We did a quick check of this board today. Main takeaways:
With the correct , we expect 0V from the DAC to result in 0 actuation on the mirror, assuming that an equal 75V goes to 2 PZTs mounted diametrically opposite on the optic. Hopefully, this means we have sufficient range to scan the input pointing into the OMC and get some sort of signal in the REFL signal (while length PZT is being scanned) which indicates a resonance.
We plan to carve out some IFO time for this work next week.
I did a quick survey of the drive electronics for the PZT OM mirrors today. The hope is that we can correct for the clipping observed in the AS beam by using OM4 (in the BS/PRM chamber) and OM5 (in the OMC chamber).
Here is a summary of my findings.
I hope these have the correct in-vacuum connections. We also have to hope that the clipping is downstream of OM4 for us to be able to do anything about it using the PZT mirrors.
pzt2 mod signals matched slider vals for both pitch and yaw
pzt2 yaw mon output = 6
pzt2 pitch mon output = 11.3
From the PZT connector-converter board we determined the following pin-outs:
X=Yaw: red=1, white=14, black=3
Y=Pitch: red=2, white=15, black=16
We believe that red is signal, white/black/shield are all ground. We also believe (although this is from the PMC PZT) that the expected capacitance of the PZTs should be in the 100's of nF range.
Here are the readings from the two PZT dsub connectors:
pin 1:14 PZT1 = ".003" on 2uF scale
PZT2 = ".184"
pin 2:15 PZT1 = ".002" on 2uF scale
PZT2 = ".202"
So we think this means (given this crappy capacitance meter) that PZT2 is showing roughly 200nF, which sounds ok, but that PZT1 is indeed bad.
So next we investigate the PZT2 driver.
Jamie and I pulled the whole PZT driver for both PZT1 and PZT2.
Koji and I found that each HV power supply (the left-most module) has 2 fuses. Both HV supplies (PZT1 and PZT2) have one blown fuse. The "T2L250A" measures low resistance for both HV supplies, but the "T250mAL250V" measures Open for both HV supplies.
I have ordered 10 pieces of each kind of fuse, Next Day shipping, from DigiKey.
We naively hoped that just replacing the fuses would fix the problem with the PZT HV drivers. Alas, this was not the case.
All of our investigations (other than visual inspections) today have been of the PZT2 module. We have not applied any electricity to any PZT1 components/modules today.
After blowing a few more fuses (not good, we know, but we really didn't know what was going on at the time and were convinced that our changes between fuse installations should prevent fuse-blowing, including removing all modules except the HV driver), we found that the YAW driver for both PZT1 and PZT2 has severe discoloration on the PCB, and several resistors and other solder joints are damaged near some high voltage regulators. Pitch on PZT1 looks a tiny bit discolored, but doesn't look totally cooked like the 2 YAW modules do. So, at least PZT1's Yaw was cooked before we started replacing fuses, since we haven't plugged it in yet today.
We then began some more methodical checks:
We bypassed the fuses by applying 10 Vpp = ~7.2 Vrms to the input side of the big transformer on the PZT2 HV driver board. (This usually sees the 120 Vrms from the wall AC, so we were looking at things with a factor ~16 attenuation from what they normally see.) We then measured things on the other side of the transformer, and made sure that they made some sense (one path for 5V stuff, one path for 15V stuff, one path for 180V stuff). One of the rectifying diode bridges (the one for HV) didn't seem to be working, and didn't seem to have all of its pins connected, as if perhaps one or more diodes inside was destroyed.
When I went home for dinner, Koji continued looking at the low voltage supply capability of the PZT2 driver. He removed the diode bridge from the HV path, and also removed the FET that lives on the output side of the HV driver board. He was then able to energize the HV driver and the non-burnt pitch module. So the +\-5 V and +\-15 V paths have been confirmed okay for PZT2's driver stuff.
What I will do tomorrow (when there is someone here to rescue me if I crispy-fry myself) is solder a wire to the now open pin of the backplane connector on the HV driver board, so that we can supply an external 180V to the pitch / yaw modules (although, obviously we won't be using the burnt yaw modules as-is). Tomorrow I'll start by applying a nice small voltage, check that things still look okay, no shorts, and then I'll slowly increase the voltage until I get to the nominal 180V.
Since the low voltage stuff on the driver board is working, once we supply an external 180V (if successful), we should be able to re-install the PZT driver and drive PZT2.
Since both Yaw modules that we have are burnt, I am proposing that we use the PZT2 HV board (which has been checked and modified this evening) with the 2 pitch modules. Since we are not actively utilizing the strain gauge sensors, the fact that the calibrations on these modules are not exactly the same (rather, that PZT1's pitch is not the same as PZT2's yaw) should not matter at all. This means that we will not be able to energize PZT1 at all, but that shouldn't be a problem. Even when PZT 2 was working, PZT1 had very, very, very limited motion through the full range of applied voltage, so having no driver connected shouldn't have an impact.
I connected a thick wire to pin 22 of the backplane connector of the transformer / power supply module of the PZT box. This is the pin that +180V is supposed to go on, to be distributed to the other boards in the crate. Last week I had drilled a hole in the front panel so the wire can come out (since no one on campus seems to have HV panel mount connectors in stock).
While the transformer module was isolated, not touching anything else, I applied (slowly ramping up) 180V DC, and it all looked good.
When I plugged the module back into the crate (first turning off and disconnecting the HV), I blew the 250mA fuse again. No HV yet, just the low voltage stuff that Koji had fixed last week. :(
We're now out of 250mA fuses, we're supposed to get a box of them tomorrow.
After the fuse-blowing fiasco earlier this afternoon, Koji and I took another look at the PZT controllers.
We put an ammeter in place of the fuse, and watched the current as we turned on the transformer module. The steady-state current with no other modules plugged in is ~15mA. However, there is a surge current right when you turn on the box which sometimes goes as high as 330mA. Since the fuse is 250mA, this explains the fuse blowing, even though Koji had already checked out the low voltage path.
The high voltage line was connected, with +180V to the HV out pin of the backplane connector, and the (-) terminal of the power supply connected to signal ground on the board.
We inserted the PITCH module for PZT2, and we started with ~10V as our "high" voltage, and slowly increased the value (current at this time was ~60mA). We also had a function generator plugged into the "MOD" input, which is where the epics slider goes, so that we should see a changing output voltage. We never saw a changing output voltage. Increasing the HV power supply didn't help.
When Koji spun the "DC offset" knob really fast and then stopped, sometimes the output voltage as measured on the connector-converter board between the white and red wires would jump up, and then settle back down. It came back to the same value that it always was, but it was bizzarre that it would jump like that. We suspect that that knob is an offset for use with the closed loop setting, so it isn't relevant for us anyway. Watching the MON output, the value never changed, even when Koji did his fancy knob twirling.
We switched to the other PITCH module, and watched the output voltage on the MON output. This time, with the function generator unplugged, so no modulation input (so we were expecting a steady DC output voltage) the number on the LCD and the MON output fluctuated wildly. We plugged in the function generator, and the fluctuations did not change in approximate amplitude or DC offset. They kind of looked the same.
So, we have concluded that (a) the PZT drivers don't work, and (b) we don't understand why. Therefore, we don't know how to fix them.
With that in mind, we are thinking of totally circumventing the PZT drivers.
I plugged in the PZT1 connector converter board, which has Koji's circuit that he made last time when PZT1 died. I plugged the ribbon cable which goes to the PZT, and the +\- 30V power supply, and the PZT responded! Just plugging in the power supply puts the PZTs near the center of their nominal range. I then put a function generator on the epics inputs for pitch and yaw (one at a time), and saw the spot move around at the ~1Hz that I was applying. Yay!
What I think I'll do for tonight - modify the other connector converter board so that I can just use 2 HV power supplies (current limited) to steer the PZT. I set up a TV monitor next to the PZT electronics (1Y3? 1Y4? I forget), and it's connected to output 20 of the video switch, so I can watch the AS camera and move the PZTs by hand. Then maybe I can try to align some stuff. (Evan is coming to work tonight, so if I electrocute myself, someone will be here to call 5000) Koji suggested buying 2 single-channel thorlabs piezo drivers, like we have on the PSL table for the FSS loop. These take in 0-10V and output either 0-75V, 0-100V or 0-150V (depending on which setting you choose). These cost $712 each. This would be a more permanent solution than me just sitting out there, since we could once again control PZT2 via epics.
Note to self:
The ENV-40 amplifiers that we have supply -10V through +150V .... so don't exceed those limits.
[ Yuki, Gautam ]
I fixed the input terminal that had been off, and made sure PZT driver board performs as we expect.
At first I ran a simulation of the PZT driver circuit using LTspice (Attached #1 and #2). It shows that when the bias is 30V the driver performs well only with high input volatage (bigger than 3V). Then I measured the performance as following way:
The result of this is attached #3 and #4. It is consistent with simulated one. All ports performed well.
The high voltage points (100V DC) remain to be tested.
SHEET 1 2120 2120
WIRE 1408 656 1408 624
WIRE 1552 656 1552 624
WIRE 1712 656 1712 624
WIRE 1872 656 1872 624
WIRE 2016 656 2016 624
WIRE 1408 768 1408 736
WIRE 1552 768 1552 736
WIRE 1712 768 1712 736
I assume this QPD set is a D1600079/D1600273 combo.
How much was the SUM output during the measurement? Also how much were the beam radii of this beam (from the error func fittings)?
Then the calibration [V/m] is going to be the linear/inv-linear function of the incident power and the beam radus.
You mean the linear range is +/-50mV (for a given beam), I guess.
The feedback signal going to the laser PZT at the X end station was measured in the daytime and the nighttime.
It's been measured while the laser frequency was locked to the arm cavity with the green light.
The red curve was measured at 3pm of 8/July Friday. And the blue curve was measured at 12am of 9/July Saturday.
As we can see on the plot, the peak-peak values are followers
daytime: ~ 4Vpp
daytime: ~ 4Vpp
It is obvious that the arm cavity is louder in the daytime by a factor of about 2.
Note: the feedback signal is sent to the PZT only above 1Hz because the low frequency part is stabilized mostly by the crystal temperature (see this entry)
What we care about is the peak-peak value of the PZT feedback signal measured on a scope for ~30 seconds.
I'll come back to the PZTs later, but I want to write down all the elogs I have found so far that look relevant.
I calibrated PZT mirrors. The ROUGH result was attached. (Note that some errors and trivial couplings coming from inclination of QPD were not considered here. This should be revised and posted again.)
The PZT mirrors I calibrated were:
I did the calibration as follows:
The calibration factor was
CVI-pitch: 0.089 mrad/V
CVI-yaw: 0.096 mrad/V
Laseroptic-pitch: 0.062 mrad/V
Laseroptic-yaw: 0.070 mrad/V
Previous calibration of the same mirrors, elog:40/8967
Kiwamu and I measure the PZT response of the Innolight this evening from 24 kHz to 2MHz.
We locked the PLL at ~50 MHz offset using the Lightwave NPRO and and swept the Innolight with the network analyzer (using the script I made; it has one peculiar property, but it does work correctly).
We will post the plot of the Lightwave PZT response tomorrow morning.
**EDIT**: As Koji pointed out, the calibration factor on this plot is WRONG. See my more recent update for the correctly calibrated plot.
The shape of the TF looks nice but the calibration must be wrong.
Suppose 1/f slope with 10^-4 rad/V at 100kHz. i.e. m_pm = 10/f rad/V
This means m_fm = 10 Hz/V. This is 10^6 times smaller than that of LWE NPRO.
(Edit: Corrected some numbers but it is not significant)
Suppose 1/f slope with 10^-4 rad/V at 10kHz. i.e. m_pm = 1/f rad/V
This means m_fm = 1 Hz/V. This is 10^7 times smaller than that of LWE NPRO.
Koji is absolutely right. I just double checked my matlab code, and saw that I divided when I should have multiplied. The correctly calibrated plots are attached here for the Innolight and the lightwave. Kiwamu and I will measure the amplitude and the jitter today.
Innolight: 100rad/V @ 100kHz => 1e7/f rad/V => 10MHz/V
LWE: 500rad/V @ 100kHz => 5e7/f rad/V => 50MHz/V
They sound little bit too big, aren't they?
The Lightwave NPRO should be around 5 MHz/V.
The Innolight PZT coefficient is ~1.1 MHz/V.
(both are from some Rick Savage LHO elog entries)
We realized that we had measured the wrong calibration value; we were using the free-running error signal with the marconi far from the beat frequency, which was very small. When we put the Marconi right at the beat, the signal increased by a factor of ~12 (turning our original calibration of 10 mV/rad into 120 mV/rad). The re-calibrated plots are attached.
Innolight 10 rad/V @ 100kHz => 1e6/f rad/V => 1MHz/V
LWE 30 rad/V @ 100kHz => 3e6/f rad/V => 3MHz/V
BTW, don't let me calculate the actuator response everytime.
The elog (=report) should be somewhat composed by the following sections
Motivation - Method - Result (raw results) - Discussion (of the results)
We realized that we had measured the wrong calibration value; we were using the free-running error signal with the marconi far from the beat frequency, which was very small. When we put the Marconi right at the beat, the signal increased by a factor of ~12 (turning our original calibration of 10 mV/rad into 120 mV/rad). The re-calibrated plots are attached.
We measured the Amplitude Modulation response of the PZTs, to find regions with large phase modulation but small amplitude modulation.
We did this by blocking 1 arm of the PLL, feeding the source output of the Network Analyzer into the PZT input of the laser in question, and reading the output of the PD on the NA. We calibrated by dividing by the DC voltage of the PD (scaled by the ratio of the AC gain to DC gain of the New Focus PD).
The AM response of the Innolight looks fairly smooth up to ~1MHz, and it is significantly below the PM response for most of its range. The region between 20 and 30 kHz shows very good separation of about 10^3 rad/RIN (and up to 10^5 rad/RIN at ~21.88 kHz, where there is the negative spike in the AM response). The region between 1.5 MHz and 2MHz also looks viable if it is desirable to actuate at higher frequencies.
The Lightwave offers very good AM/PM separation up to about 500 kHz, but becomes quite noisy about 1MHz.
I measured a jitter modulation caused by injection of a signal into laser PZTs.
The measurement has been done by putting a razor blade in the middle way of the beam path to cut the half of the beam spot, so that a change of intensity at a photodetector represents the spatial jitter of the beam.
However the transfer function looked almost the same as that of amplitude modulation which had been taken by Mott (see the entry).
This means the data is dominated by the amplitude modulation instead of the jitter. So I gave up evaluating the data of the jitter measurement.
I redid the PZT Phase Modulation measurement out to 5 MHz for both the Innolight and the Lightwave. The previous measurement stopped at 2MHz, and we wanted to see if there were any sweet spots above 2MHz. I also reduced the sweep bandwidth and increased the source amplitude at high frequency to reduce the noise (the Lighwave measurement, especially, was noise dominated above 1MHz). I also plotted the ratio of PM/AM in rad/RIN, since this is the ultimate criterion on which we want to make a determination.
It looks like there is nothing extremely useful above 2MHz for either laser. There are several candidates for the lightwave at about 140 kHz and again at about 1.4 MHz. The most compelling peak, however, is in the innolight at 216 kHz, where the peak is about 2.3e5 rad/RIN.
Below about 30kHz, the loop suppresses the measurement, so one should focus on the region above there.
Using a PDA255 on the PSL table, I measured the amplitude response of the NPRO PZT, sweeping from 10kHz to 5 MHz.
I took a run with the laser beam blocked. I then took three runs with the beam unblocked, changing the temperature of the laser by 10 mK between the first two runs and by 100mK between the second and third runs.
At the end of the night I turned off the network analyzer and unplugged the inputs. I'm leaving it near the PSL table, because I'd like to take more measurements tomorrow, probing a narrow bandwidth where the amplitude response is low.
On the PSL table, I'm still monitoring the reflected light from the cavity and the transmitted light through the cavity on the oscilloscope. I'm no longer driving the NPRO temperature with the lock-in.
I closed the shutter on the NPRO laser at the end of the night.
I'll log more details on the data tomorrow morning.
PZT1 started railing in the pitch direction and because of this TRY doesn't go more than 0.7. I will leave it as it is for tonight.
Tomorrow I will shift the alignment of the MC to make the PZT1 happier.
PZT1, the one with Koji's custom mid-HV driver (#5447), is getting degraded.
Jamie and Koji pointed out that we need to be doing the in-vac alignment with the PZTs at the center of their ranges. Also, we confirmed that they were set to "closed loop off", so the strain gauges were not supplying any feedback.
PZT1 was set to 0 for both pitch and yaw, since it has a very limited range of motion right now, so 0 is close enough.
For PZT2, Koji and I moved the slider in pitch and yaw, and watched the LCD output monitor on the PZT driver at the bottom of 1Y3. We saw the value on the LCD change between slider values +4 to -6 for PZT2 yaw, so it is set to -1 as the center. We saw the value on the LCD change between slider values -4 to +5 for PZT2 pitch, so it is set to +0.5 as the center. Beyond these slider values (the sliders all go -10 to +10), the LCD value didn't change, either at 0, or at the maximum.
Since PZT1 doesn't really move, this shouldn't affect any of the alignment work that Suresh and I did last night, although we should quickly confirm tomorrow. On the agenda for tomorrow is adjusting PZT2 such that we hit the center of PR2 (and hopefully that will also put us through the center of the PRM target, if the alignment was done well enough last time), so it's okay that we have only now set it to the center of its range.
As the PZT1 has not been functional, I have been aligning the Y arm to the input beam instead of aligning the beam to the Y arm.
It turned out that this procedure leads to two extra works everytime after alignments of the Y arm:
The polarity for controlling the PZT1 PITCH seems to have flipped for some reason.
Last night I noticed that PZT1 didn't work properly
I am not sure what is going on. Today I will try localizing the cause of the problem.
As far as I remember it was perfectly working at the time just after we readjusted the OSEMs on MC1 and MC3 (Aug 23th)
The symptoms are :
+ No response to both pitch and yaw control from EPICS (i.e. C1:LSC-PZT1_X and C1:LSC-PZT1_Y)
+ When a big value (-3 or so) from EPICS was applied, the PZT1 mirror suddenly jumped.
However it turned out it just corresponded to a state where OOR (Out Of Range) LED lights up.
I did some brief checks :
+ checked the voltage going into the HV amplifiers' "MOD" input. Those are the voltage coming out from DACs and controlled from EPICS.
--> looked healthy. They went from -10 to 10 V as expected (although the HV amp takes up to only +/-5V).
+ swapped the ''MOD" input cables such that C1:LSC-PZT1 controls the PZT2 HV and vice versa.
--> The PZT2 mirror was still controlable, but the PZT1 mirror still didn't move. So the DAC and EPICS are innocent.
+ swapped the D-dub cables, which are directly going into the feedthroughs, such that the PZT1 HV drives the PZT2 mirrors and vice versa.
--> the PZT2 mirror became unable to be controlled. For the PZT1 mirror, only PITCH worked smoothly.
The PZT driver is now in place. The actual PZTs are not connected yet!
It is accommodated on Ben's connector adapter board.
The panel has additional connectors now: two inputs and a power supply connector.
The supply voltage is +/-30V (actual maximum +/-40V), and the input range is +/-10V
which yields the output range of -5V to 30V. The gain of the amplifier is +2.
It is confirmed that the HV outputs react to the epics sliders although the PZT connector is not connected yet
so as not to disturb the locking activity.
When we engage the PZT connector, we should check the HV outputs with an oscilloscope to confirm they
have no oscillation with the capacitances of the PZTs together with the long cable.
[Manasa, Jamie, Jenne]
PZT1 has been removed, and is wrapped in foil and stored in a (labeled) plastic box.
We beeped the cable between the cable holder bracket on the in-vac table, and the outside of the feedthrough. Things are mirrored, so pins 1,14 (one edge on the feedthrough) go to pins 13,25 on the in-vac cable bracket.
Tip Tilt, serial number ### (Manasa will get the serial number and put it in the elog) was taken out of the cleanroom, for use as TT1.
We checked the epics controls from the TT screen that Jamie made a while back (accessible from the ASC tab on the sitemap) to the output of the AI board. Things were very weird, but Jamie fixed them up in the model, then rebuilt and restarted the ASS model so that now the epics channel corresponding to, say, UL actually actuates on the UL output of the boards.
We tested the cables from the rack to the feedthrough, and discovered that they are also mirrored, to undo the mirroring between the feedthrough and the in-vac bracket.
Jamie made an adapter cable to take the pinout of the coil driver boards correctly to the pinout of the quadrupus cable, through this double-mirroring (i.e. no net mirror effect).
We set up a laser pointer on a tripod outside the door of the MC chamber (where the access connector usually is), and pointed it at the back of the TT. Den or whomever put the cable on the TT didn't follow the diagram (or something got messed up somewhere), because when we actuate in pitch (+ on the uppers, - on the lowers), we see the TT move in yaw, and vice versa.
We are in the process of removing the quadrupus from the TT, figuring out which connector goes where, putting it on correctly, and re-testing.
Depending on how far things get tonight, Jamie and Manasa may ask Steve to help them remove the BS door, so they can get started on replacing PZT2 with TT2.
I have fixed TT1 close to what it's position looks like in the CAD drawing. Only 2/3 of TT1 rests on the table...so we need to be extra careful when we will move it for alignment.
Serial Number: SN 027
dcc number: D1001450-V2
We are still in the process of removing the quadrupus from the TT, figuring out which connector goes where, putting it on correctly, and re-testing.
We closed the IMC chamber with light doors calling it a day!
- We have checked the situation of the broken Piezo Jenna PZT (called PZT1)
- Tested PZT1 by applying a dc voltage on the cables. Found that pitch and yaw reasonably moving and the motions are well separated each other.
The pitch requires +20V to set the IPPOS spot on the QPD center.
- Made a high-voltage (actually middle voltage) amp to convert +/-10V EPICS control signal into -5 to +30V PZTout. It is working on the prototype board and will be put into the actual setup soon.
- The Piezo Jenna driver box has 4 modules. From the left-hand side, the HV module, Yaw controller, Pitch controller, and Ben abbot's connector converter.
- We checked the voltage on Ben's converter board. (Photo1)
It turned out that the red cable is the one have the driving voltage while the others stays zero.
- We hooked a 30V DC power supply between the red cable and the shield which is actually connected to the board ground.
- Applying +/-10V, we confirmed the strain gauge is reacting. If we actuated the pitch cable, we only saw the pitch strain gauge reacted. Same situation for yaw too.
- Kiwamu went to IPPOS QPD to see the spot position, while I change the voltage. We found that applying +20V to the pitch cable aligns the spot on the QPD center.
- I started to make a small amplifier boards which converts +/-10V EPICS signals into -5V to +30V PZT outs.
- The OPAMP is OPA452 which can deal with the supply voltages upto +/-40V. We will supply +/-30V. The noninerting amp has the gain of +2.
- It uses a 15V zener diode to produce -15V reference voltage from -30V. This results the output voltage swing from -5V to +35V.
The actual maximum output is +30V because of the supply voltage.
- On the circut test bench, I have applied +/-5V sinusoidal to the input and successfully obtained +5V to +25V swing.
- The board will be put on Ben's board today.
[Jenne, Evan, Den]
MC REFL beam is back on the PD, and the mode cleaner locks. It looks like we're a little high on the MC Refl camera, but the MC spots were measured, and don't look like they changed from Friday (or maybe Monday?), the last time they were measured. We took this to be acceptable MC alignment, and did not touch the PSL table's pointing.
The laser power reduction optics were removed, and placed out of the way on the PSL table (where do they belong?). PSL-POS and PSL-ANG aren't quite perfectly centered, but a beam dump had been in the way of that path, so I don't know if they drifted bad, or if it was a sudden thing. The beam is still hitting the QPDs though. After removing the beam power reducing optics, we recentered the MC REFL beam on the REFL PD, still not touching any PSL alignment. MC mirrors were aligned (Den did this work while I showed Evan around, so I don't know by how much), and MC Trans was maximized (really MC Refl was minimized, making sure that the unlocked MC Refl was the usual 4.something units on the EPICS readback.
We turned on the PZT high voltage supplies for the output steering PZTs and for the input steering PZTs. We left the OMC locking PZT supplies off, since we're still not using the OMC. Sadly, the beam coming out of the AS port looks clipped somewhere. [SELF: attach the videocapture shot when you get to work tomorrow] We tried moving PZT2's sliders, but nothing happened!!! I can move BS and the ITMs to get the beam mostly unclipped, but I really need to be able to move the PZTs, or at least one of them. IPPOS and IPANG beams are hitting the QPDs (although they're not centered perfectly), so the PZTs came back mostly to the same positions, but not exactly. Evan and I sat next to the input steering PZT controllers in 1Y3, and moved the sliders around. For most of the range, nothing changes on the LCD screen for either PZT2 pitch or yaw. Yaw can make 2 small steps near the far negative side of the slider, but nothing happens for most of the slider. Pitch really doesn't do anything for any part of the slider. We ensured that the LED labeled "CL ON" was not illuminated, next to the button labeled "closed loop", for all 4 controllers (PZT1 and 2, pitch and yaw). Sad!! I don't know if the LCD screen on the front panel of the PZT controllers is a readback of signal supplied to the PZTs, or of the strain gauges. I really hope it's the controller that's not working, rather than the PZTs themselves. The PZTs were fine before we vented, and Koji and I did our centering of the PZT range check during the vent, so they were fine then. What happened??? All PZT high voltage supplies were off during the pump-down. I turned them off yesterday, and Evan and I turned them back on tonight around 9:30pm or 10pm. What else could make them bad?
Without being able to move PZT2, just using BS and / or ITMs, I was unable to completely make the beam look nice on the AS camera. I came close, but it still seems a little bit funny, and I had to move the suspended optics quite a bit to find that place. This is not good.
We applied some volts across both the pitch and yaw pin sets of the ribbon cable that goes to PZT2. We ended up with ~40V yaw and ~14.5V pitch. That was the nice happy center of the clipping that we can see on the AS camera. Once we found the center of the PZT clipping range with the ITMY beam, we recentered the AS camera (actually, this took a few iterations, but now it's good).
We then aligned MICH, but aren't able to get it to lock. Before falling asleep, we have decided to align the PRM and SRM, so right now we have a flashing DRMI. Both the SRMI and PRMI look a little funny the closer you get to 'good' alignment, so I'll investigate a little more tomorrow, and include pictures. (The video capture script has barfed again, and I'm not in the mood to deal with it today.)
I connected PZT1 and PZT2 to a slow front end machine c1iscaux.
Now we are able to align these PZTs from the control room via epics.
Since we removed C1ASC that was controlling the voltage applied on the PZTs, we didn't have the controls for them for a long time.
So Rana and I decided to hook them up to an existing slow front end machine temporarily.
(probably the best solution is to connect them to C1LSC, which is fast enough to dither them.)
We actually found that c1iscaux is the proper machine, because it looked like it used to control the PZTs a long long time ago.
Moreover, c1iscaux still has DAC channels named like C1:LSC-PZT1_X, and so on.
Below shows a screen shot of the medm screen for controlling the PZTs, invoked from a button on sitemap.adl ( pointed by a black arrow in the picture below)
The current default values are all zero at the right top sliders.
A package labelled 'UPS Ground' has arrived.
Today I learned some important circuit-building lessons while testing my photosensor circuit box (i.e. how NOT to test a circuit and, conversely, things that should be done instead).
I blew my first circuit today. The victim is in the photo below (bottom 7805 voltage regulator). The plastic covering fell off after I removed the fried regulator. After checking various components, I figured out that I blew the circuit because I had forgotten to ground the regulator. Although this was very unfortunate, I did make an important discovery. While testing the voltage output of the 7805 voltage regulator (I put a new one), I discovered that contrary to the claims of the datasheet, an input voltage of 5V will not produce a steady 5V supply. I found that at 5V, my regulator was only producing 4.117 V. I was using a 5 V supply because I wanted to use only 1 power supply (I was using a two-channel power supply that had a fixed 5V output to produce the +15, -15, ground, and 5 V I need for my photosensor circuit box). After seeing this, I got a second power supply and am now using 10V to as an input for the regulator to produce 4.961V. I found that from a voltage range of 10V to 15 V, the regulator produced a steady 4.961 V supply. I have decided to use 10V as an input. My newly-grounded voltage regulator did not smoke or get hot at 10V.
After several more debugging trials (my LED was still not lighting up, according to the infared viewer), I learned another painful lesson. I learned DO NOT USE CLIP LEADS TO TEST CIRCUITS!!!! Initally, I was powering my circuit and making all of my connections between the photosensor head (2 photodiodes and 1 LED) with clip leads. This was a BAD IDEA BECAUSE CLIP LEADS ARE UNSTABLE AND IT IS VERY EASY TO SHORT A CIRCUIT IF THEY ACCIDENTALLY TOUCH! I did not realize this important lesson until my photosensor circuit was once again burning. Confused as to why my circuit was once again burning, I foolishly touched the voltage regulator. As you can see on the top voltage regulator in the photo below, my finger left its mark on the smoldering voltage regulator. As you cannot see the wincing on my face as I try to type this long elog, I will painfully type that the voltage regulator left its own mark on my finger (an ugly sore little welt). Suresh has taught me a valuable lesson: WHEN DEALING WITH SOMETHING OF QUESTIONABLE/UNKNOWN TEMPERATURE, USE YOUR NOSE, NOT YOUR FINGER TO DETERMINE IF THAT COMPONENT IS HOT!!!!
To make my circuit-testing safer, upon the suggestion of Suresh, I have since removed the clip leads and inserted a 12 pin IDC component (pictured below). There are 12 pins for the 6 inputs I will get from each of the 2 photosensor heads. I have requested orders for a 16 pin IDC connector, 15 pin Dsub male part, 15 pin Dsub feed-thru, 9 pin Dsub male part (2), and 9 pin Dsub feed-thru (2). After receiving these components, I should be able to safely test my circuit.
In the meanwhile, I can explore SimMechanics and try to figure out how to use the accelerometer
There is should be a few IDC connectors in the lab (and some ribbon cable) using which you can proceed with the testing of the circuit, if you prefer. If not we can get them from our ever helpful electronics division at Downs. In any case there is no need to lose time waiting for parts to arrive.
I expanded the previous panels to 6U height for the new DAQ chassis we're buying for the upgrade. I figure it's best if we stick to the modular design, so I'm showing a panel for 8 BNC connectors as an example. The front panel has 12 slots, the back has 10 plus power connectors, switches, and the ethernet plug.
I moved the power switch to the rear because it's a waste of space to put it in the front, and it's not like we're power cycling this thing all the time. Note that the unit only requires +24V (for general operation, +20V also does the trick, as is the situation for ETMX) and +15V (excitation field for the binary I/O modules). While these could fit into a single CONEC power connector, it's probably for the better if we don't make a version that supplies a large positive voltage where negative is expected, so I put in two CONEC plugs for +/- 15 and +/- 24.
I want to order 5-6 of these as soon as possible, so if anyone wants anything changed or sees a problem, please do tell!
The VEA vertex laptop, paola, has a flashing orange indicator which I take to mean some kind of battery issue. When the laptop is disconnected from its AC power adaptor, it immediately shuts down. So this machine is kind of useless for its intended purpose of being a portable computer we can work at optical tables with. The actual battery diagnostics (using upower) don't report any errors.